Electromagnetic horn



Jan. 25, 1955 J. WHITE ET AL ELECTROMAGNETIC HORN 2 Sheets-Sheet 2 Filed Feb. 5, 1952 JOE WH/ TE:

INVENTOR BY CLAeE/vcE-J/(ame ,t/w, ATTOENE v.5

United States Patent ELECTROMAGNETIC HORN Joe White and Clarence J. Keller, Anderson, Ind., as-

signors to General Motors Corporation, Detroit, Mich., a corporation of Delaware Application February 5, 1952, Serial No. 269,966

9 Claims. (Cl. 340-388) This invention relates to improvements in sound signals or horns having a diaphragm actuated by an electromagnet energized by an intermittent current.

It has heretofore been customary to provide a sound signal switch a core made from E-shaped laminations held together by rivets which require a drilling operation and a disc grinding operation; to provide an armature stud or rod which is made on a screw machine which has three sizes of threads which require nuts; to provide a base made of relatively thick steel; and to provide a circuit breaker by which current through the magnet is interrupted periodically, the circuit breaker being actuated by one of the nuts vibrating with the diaphragm.

The main object of this invention is to provide a sound signal or horn of the magnetically actuated diaphragm type, that is light, durable and economical in construction; that may be readily assembled and adjusted by a bendable part and that, at the same time has fine tone qualities.

In carrying out the above objects, we have by refinements in design, construction and arrangement of the various elements provided a less expensive magnetic circuit by the use of a box-like frame with four pole faces made from punch press operations and a center core sleeve made on a header; by the use of an armature stud made on a header which eliminates all threads; and by using a new method of adjusting the horn current by the bending of sheet metal rather than adjustment by a nut and a lock nut together with suitable and convenient means for supporting the circuit breaker on the frame or base of the horn. With the new design and refinements the thickness of the steel used for the base and the supporting means for the circuit breaker in previous construction of the same type is reduced thirtythree percent.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings wherein a preferred embodiment of the present invention is clearly shown.

In the drawings:

Fig. l is a plan view of a horn embodying the improvement of the present invention.

Fig. 2 is a sectional view taken on line 22 of Fig. 1.

Fig. 3 is a detail view of the armature and bracket shown in Fig. 2 and looking in the direction of arrow 3.

Fig. 4 is an enlarged sectional view of armature assembly taken on line 4-4 of Fig. 3.

Fig. 5 is a plan view of the horn base.

Fig. 6 is a sectional view of base taken on line 66 of Fig. 5.

Fig. 7 is a blank form in which a field frame is formed.

Fig. 8 is a plan view of the frame.

Fig. 9 is a view of frame looking in direction of arrow 9 of Fig. 8.

The signaling device comprising the present invention and as shown in the drawings, comprises a frame or base member 20 made from comparatively thin metal pressed to the desired form. The base is formed to provide a central cup-shaped section having :a bottom wall 21. The cup-section has an outwardly extending flange 22, said bottom wall 21 is formed with an opening 22a having an inwardly extending arm 23 indicated in dot and dash lines. This arm 23 is bent angularly relative to the bottom wall to provide a platform or shelf 1 core sleeve 51. The ends hereinafter.

bottom wall 21 is also formed with spaced portions bent angularly relative to the bottom wall for providing attachment lugs 25. A U-shaped bracket 26 of relatively thin sheet metal is attached to the bottom wall 21 and to the platform 24 by projection welding. For this purpose the bottom wall 21 is provided with spherical bosses or projections 27. The platform 24 is also provided with spherical bosses, not shown. The legs of the bracket 26 extend through the opening 220 of bottom wall 21. The legs have side portions 29 which abut against the underside of section 21 while the yoke or shelf 28 abuts the upper face of the platform 24. By this arrangement a rigid support, having three sides is provided for mounting a circuit breaker assembly to be described.

A resistor assembly is attached to the base bottom wall 21. This assembly includes a disc resistor 30, a terminal clip 31, an insulating washer 32, a metal washer 33, a rivet 34 received by a hole in the base, and a conducting sleeve 35 surrounding the rivet 34. After these parts or elements are assembled to the base as shown in Fig. 2, the upper end of the rivet 34 is upset. The underside of the resistor 30 is grounded on the bottom wall 21 while the upper side of the resistor is electrically connected with the terminal clip 31 which is electrically connected with an insulated wire 36.

The opening 22a in the bottom wall 21 receives an electromagnet assembly including a box-like container formed from a blank 37 of relative thin sheet metal shown in Fig. 7. This blank 37 has a rectangular base portion 38 provided with an opening 39 and two apertures 40. The blank is bent along the dot-and-dash lines to provide the rectangular base 38 shown in Fig. 7, and to form opposite side Walls 41 and 42 and end walls or flanges 43 and 44 see Fig. 8. The edges of the side and end walls are coined by a punch press or machined to provide smooth pole faces arranged in the same plane. The side walls 41 and 42 have oppositely disposed integral ears or extensions 41a and 42a, respectively engageable with and attachable to respective lugs 25 for securing the container to the bottom wall 21.

Referring to Fig. 2 a cold headed hollow core or sleeve is attached to the base 38. The sleeve 57 has an enlarged flange or head 52 at one end while the opposite end portion of the sleeve is reduced at 53 which is received by the opening 39 of the base 38 and riveted over the underside of the base 38. A coil 54 surrounds the core sleeve and is disposed between the head 52 and the base 38. The coil is built up of coiled wire in the well-known manner, and is suitably insulated from the of the coil pass through the openings 40.

The armature assembly shown in Figs. 2, 3 and 4 comprises a novel design of rod or stud cold formed by a header. The rod 60 is provided at one end with an enlarged flange portion or head 61, a first reduced portion 62, a second reduced portion 63 and a third reduced portion 64. The portion 62 receives a bracket 65 having a base 66 provided with a bendable arm 67. The arm 67 is bent at an angle to the plane of the base as shown in Fig. 3. The arm 67 is cut to provide an extension 68 which is bent at substantially right angles to the plane of the arm 67 and toward the base 65. The extension 68 is formed in this instance with a spherical cam portion 69, the purpose of which will be described The portion 62 also receives a leaf spring '52, a plate 71, having a stop flange 73 and an armature When these parts 65, 70, "71 and 74 are assembled on the reduced portion 62 it is circularly staked into tapered recess 75 in the armature 74 as clearly shown in Fig. 4.

24 spaced from and parallel to the bottom wall 21. The

The staked portion is flush with the flat underside of the armature 74. The leaf spring is provided with three holes which register with three holes in the end 24 and three holes in the platform of the bracket 26. These holes receive rivets 76 by which the leaf spring 70 and other parts of a circuit breaker assembly 77 are attached to the platform.

Before the electromagnet assembly is secured to the base 21, the armature assembly is attached with a diaphragm assembly 80. This is accomplished by passing the rod 60 through the sleeve core 51 with the reduced portion 64 of the rod 60 receiving. a plain metal washer 81, a slightly dished metal washer 82, a metal diaphragm 83, and a plain metal washer '84. These parts are clamped a a t a hs lds 85. w ups ttin th ed ce porti n 64; sst 861. a t e W h ef st ia ta m a sembl i at ched o he u tature assembly, the diaphragm aligned with the frame base 20 in such a way thatnotches 37 provided by the diaphragm will register with holes provided in a flange 2 2 of frame 24}. Then the diaphragm is attached to the, frame flange permanently by spot welding at a plurality nines d n e ros 9: n d lines shqwn. in

1g. "The circuit breaker assembly '77 is then attached to the bracketz ofThis is accomplished by placing a loose stack or asseijbly of parts, which includes the leaf spring 71), a'djaceritand in contact with the shelf of the bracket 26. This stack includes the leaf spring '74), an insuiating washer or spacer 9.6, a terminal 91, a connector plate 9 2, ai1 insulating spacerv 93, a connector plate 94, a leaf spring 95, an insulatingplate96, a bracket 97 supPorti g acoritact fi normally enga'gedby a contact 99 attached to leaf spring 95 and projecting through a hole providtl in the plate as. Three rivets 76 secure the stack of parts t the W h sf l e te d r m e sh i e 79 t th upper face of the bracket 97. The lower end of the rivets, as viewed in Fig. 2 are upset against the yoke or, bracketZe in order to secure the stack of parts to the end of arm 2.3,. The heads cirf the rivets contact the bracket 97 sothat contachStti is connected to ground through bracket 97', rivets'76 and 23 of frame 2 6 whichis grounded by itsmounting upon the frame of thevehicle which a ground strapconnects with a terminal of a storage battery. 4

The terminal 91, which is electrically connected with the plate 92' has its free end bent downwardly, and said on is provided with a cup shaped member Hi5. The cup member receives a screw me for attaching a clip 197? to one end ofa Wire M18. After the circuit breaker assembly is attached to the bracket thevarious reads in), and iii r the coil 54 and lead 36 er the resistor are attached withdhe terminai plates92and 9,4, Asshown inFig. l the terminal92 is providedwith i-sh'aped tangs 92a and 92b and terminal 9 is provided vi ithtarigs iirand 94b The insulation oi coillead wire llQis placed within the folds oftangs QZaandthe bare endof wire iii is'placed in afold of tang 92b. "The insulation of'coil lead and the irisulations of resistor lead sears placed in the tangs 94/11 and the hatred ends of these leads are placed within the folds of tangs 9.4b. Since terminal plate engages leaf srin "contact is connectedto c011 lead 111 andl'eadof resistopwhich is grounded. Therefore normally closed contacts short circuitthe resistor when contact 92 sop arates from contact, the'resistorbecomes effective to reduce arcing at the contacts.

'After thecircuit breaker assembly is attached to the bracket the arms dir and 42a of the horn magnet are welded to the lugs 25. Before the welding operation, the armaturearid the pole faces of the electromagnct are located a definite distance apart. A metal shim not shown, of predetermined thickness is placed between the armature and the pole faces of the box-like frame and electric current is caused to pass through thecoil thereby causing the core sleeve to move toward the armatnreand bear firmly against the shim to provide the correct air gap. While the coil is energized the cars 4112 and 42g are welded to the lugs 25 by virtue of the spherical portions carried by the ears which melt to unite the ears with respective lugs 25.

After'the welding operation, the arm 67 is bent along the point x Fig. 3 causing the cam portion 69 of arm to adjust the amount of separation of'the contact 99 from contact 98. This adjustment is made for the purposeof obtaining a certain current flow through the coil before contact separation, thereby determining the amount of electrical energy produced by the electromagnet and consequently the volume of the sound of the horn. For this purpose the cam portion is adjusted so that normally there is a predetermined clearance, for example .010" between it and the nonconducting plate.

The frame is secured to a projector assembly. In this instance the projector assembly includes an upper shell lilland alowershell 121 which are secured together by rivets 122, integral with the upper shell. These shells provide a spiral sound passage or column 123 which starts at the diaphragm chamber 124 and ends with the shell or trumpet end 125. The projector assembly together with a gasket 127 are attached to the base flange by rivets.

A back shell 130 is mounted in the base 20 to protect the vibrating parts. The shell 136 has tangs 131 which fit in notches 13.2 of flange. 133 provided by the upper shell and bent over. The shell 134} is provided with an opening lined with a rubber-like grommet 135 through which proje'ctsthe cuppeclpart of terminal 91.

In operation, it is apparent that the attraction of the armature by. thev magnet will cause the cam surface which contacts'the insulating strip to move the leaf spring 95 with it to separate contact 99 from contact 8. The leaf spring '70 is easily flexed and offers little resistance to the movement of the armature 74. When the contacts 29,, 98 separate, the spring 7%, assisted by the. diaphragm, will carry the armature 7,4; and the bracket 65to. a'posi: tion to permit closing'ofthe contacts.

While th embodiment of the present invention as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted.

Whatisclaimed'is as iollowsz 1 A composite supporting device consisting of a base anda container attached to, the base, said base being a sheet metal, cup-shaped'member' having an outwardly etc tending "annular flange; 'a' core and a coil attached to, the containerian opening formed in the bottom wall or the member for re'ceivingthe container; a portion of said bottom being bent angularl y relative to saidbottom wall to iorma platform spaced from and parallel with said bottom wall, spaced portions of said bottom, wall, bent angiilarly relative to said bottomwall for providing attachment lugs for the container which is made of sheet metal comprising a base for supporting the core and coil; said base haying a pair of spaced integral end walls and a pair of spaced integral side walls with edges of all walls being 'machined so that all of the. edges of said walls are in the same plane, said side walls having oppositely disposed integral ears engageable with and attach able to respective lugs for securing the container to the base; a diaphragm secured to thefannular fiangfi; a rod passing through the. core. attached to the diaphragm; an armature attached to the, rod; and a circuit breaker assembly attached to, the. platform.

2.'In combination with a support having spaced integ'ral upstanding lugs; a sheet metal frame having a rec.- tahgular base provided with an opening and having a plurality of integrally formed upstanding flanges defining a box-like, structure, the edges. of said flangesbeing coined and arranged in thesame plane, two of said, flanges in opposite relation. having oppositely disposed extensions engageable'with and attachable to the lugs for securing thefifame to, the support; a hollow core having a reduced portion at one. end received. by the opening; a collar associated with core; seen surrounding the core disposed between the collar and the base; and means including portions of the reduced portion of they core for securing the core to the base.

3. A composite supporting device for sounding signals consisting oi a base and a container attached to said base, saidbase. being aslieet metal, cupshaped element having outwardly. extending annular flange. an open ing formed in the bptto tn Of. said cup-shaped ele ment for receiving the. container, a portion ofsaid bottom wall; being bent angularly. relative to said wall: to form a platform spaced from and parallel with said. wall; a separate stiffening bracket having portions rigidly attached to said platform and to the bottom wall of the base; spaced portions of; said. bottom wall bent angula rly relative to said wall for providing attachmentlugs for the container which is made of sheet metal and. consists of a rectangular base on two opposite sides of which integral angular walls are provided the edges of which are in the same plane, the two other opposite sides of the container being integral angular walls the outer edges. of which are in parallel and in the same "plane as the first mentioned angular. wall edges. said two other opposite walls havingoppositelydisposed integral ears. engageable with and attachable to the said spaced angular portions of the base. for securing. the container to. the. base,

4. A composite supporting device for use. in electrical devices consisting ofabase and: a container attached to said base, said base being a relatively thin sheet metal cup-shaped element having an outwardly extending an nular flange; an opening formed in the bottom wall of the cup-shaped element for receiving the container, portions of said bottom wall being bent angularly relative to said bottom wall for providing attachment lugs for the container which is made of sheet metal and consists of a rectangular base on two sides of which integral angular portions are provided the edges of which are in a like plane, the two other opposite sides of the container being integral angular walls the outer edges of which are parallel with and in the same plane as the first mentioned angular portions, said two opposite sides having oppositely disposed integral ears engageable with and attached to the said spaced angular portions of the base for securing the container to the base.

5. In a sound signal the combination of a base and a bracket attached to the base, said base being of sheet metal; an opening formed in the base for receiving the bracket, a portion of said base being bent angularly relative to said base to form a platform spaced from and parallel with one side of said base for providing a support for the bracket which is made of sheet metal and bent into U-shape with the yoke of the bracket rigidly attached to the platform, said arms of said bracket having side extensions engaging the opposite side of the base and rigidly secured to the base.

6. In a sound signal the combination comprising a base, said base being a sheet metal, cup-shaped member having an outwardly extending annular flange; an opening formed in the bottom wall of the cup-shaped member for receiving a container; lugs carried by the bottom wall; an electromagnet attached to the lugs, said electromagnet including a box-like frame made of sheet metal, said frame comprising a rectangular base having a pair of angular spaced end walls and a pair of angular spaced side walls the outer edges of which are in the same plane, one pair of said walls having oppositely disposed ears engageable with and attachable to the lugs for securing the frame to the base; a core and a winding; and means including portions of the core for securing the core to the base of the frame.

7. An electromagnet for an electrical device comprising, a container made of sheet metal, said container comprising a rectangular base having a central opening, four integral upstanding longitudinal flanges on the periphery of the base, said edges of the flanges being machined to form smooth faces in the same plane; two of said flanges having oppositely disposed integral ears capable of being attached to portions of a support for securing the container to said support; a cold headed hollow core having an integral collar at one end and a reduced portion at the other end received by the opening in the base; a coil surrounding the core and disposed between the collar and base; and means including portions of the reduced portion of the core for securing the core to the base.

8. In combination with a support carrying spaced upstanding projections; a sheet metal frame having a base; a plurality of flanges carried by the base, the free edges of the flanges having surfaces arranged in the same plane, certain of said flanges having extensions engageable with and attachable to the projections for securing the frame to the support; a hollow core supported by said frame and having a collar at one end and having the other end associated with the base of the frame; a coil surrounding and carried by the core and disposed between the collar and the base; and means for securing the core to the base of the frame.

9. An electromagnet for an electrical device comprising in combination, a container comprising a rectangular base having a central aperture and four upstanding longitudinal flanges arranged around the periphery of the base, said flanges having faces in the same plane, two of said flanges including oppositely disposed ears thereon adapted to be attached to portions of the base for securing the container to the base, a core having an immovably disposed collar at one end thereof and a reduced diameter portion at the other end adapted to be received in an opening in said base, a coil surrounding the core and isposed between the collar and the base, and means in cluding portions of the core adjacent the reduced diameter portion thereof for securing the core to the base.

References Cited in the file of this patent UNITED STATES PATENTS 2,189,581 Hicks et a1. Feb. 6, 1940 2,227,289 White et a1. Dec. 31, 1940 FOREIGN PATENTS 116,435 Australia Ian. 12, 1943 

